The pharmaceutical industry has long used a variety of machines for forming by compression medicinal tablets from suitably prepared powders and such machines have normally employed tooling, often called punches, for contacting such powders and effecting such compression. Inasmuch as such tablets are usually of a rounded, or partially rounded, external contour, said punches will normally have a concave tip on the working end thereof to form the tablet to the desired shape. Further, such punches will frequently have embossed or debossed indicia, such as a symbol, code number or a letter, to produce corresponding recessed or elevated indicia on the tablet surface. This indicia, thereby placed onto the tablet surface, is often very small and the recesses in or elevations on the tablet contacting surface of the punch must be clean and sharp in order to produce an attractive looking product and in fact often in order for the indicia to be readable at all. However, in the normal course of use, the working surfaces of such punches usually become rough and frequently even pitted or otherwise disfigured. This results in an unattractive appearing product, or even one in which the indicia is actually unreadable, and hence the working surface of the punch must in some manner be cleaned and/or repolished to restore it to its original smooth condition before it is acceptable for continued use. However, with effective cleaning and polishing, the useful life of a given punch or set of punches can be greatly extended.
This problem has long been recognized and a variety of means have been proposed for effecting such cleaning and repolishing. The cleaning is necessary for the removal from the punch face of bits of product, i.e. the above-mentioned powders, which may cling thereto and the polishing is necessary for the removal of undesired pits, scratches and other irregularities from the product contacting surface or surfaces of the punch face.
Such previously known methods of cleaning and/or polishing have normally been mechanical in nature but have been difficult to carry out with respect to the relatively small concave surface characteristic of tablet punches and have often been very difficult to carry out effectively with respect to the embossing or debossing indicia therein provided for placing the above-mentioned indicia onto a tablet surface. Further, such cleaning and polishing as has been known in the past has seldom been uniformly effective on such punch surfaces and has been particularly lacking in uniform effectiveness with respect to such indicia.
Accordingly, the objects of the invention include:
1. To provide a method and apparatus for cleaning and polishing the working surface or surfaces of the tooling, usually punches, employed by the pharmaceutical industry in tablet-compressing machines.
2. To provide a method and apparatus, as aforesaid, which will be effective in uniformly polishing the tablet contacting surface, usually a concave surface, at the working end of such punches.
3. To provide a method and apparatus, as aforesaid, which will be effective for uniformly polishing also the embossing or debossing often appearing in such surfaces for the placement of various desired indicia onto the surface of a tablet.
4. To provide a method and apparatus, as aforesaid, which will operate quickly and efficiently and can be handled by personnel relatively unskilled in polishing techniques, as contrasted to the high level of skill required of personnel carrying out mechanical polishing procedures.
5. To provide a method and apparatus, as aforesaid, in which a large number of such punches may be conveniently and easily polished simultaneously.
6. To provide a method and apparatus, as aforesaid, which will produce results of both high quality and a high level of uniformity, such uniformity being both with respect to the entire surface of a given punch and with respect to the surfaces of each of a plurality of punches.
7. To provide a method which can be carried out by apparatus, and to provide such apparatus, which is of sufficient mechanical simplicity as to be easy to operate, capable of frequent and trouble-free use over a long period of time and, further, of sufficient simplicity as to be capable of manufacture and maintenance at a low cost.
8. To provide apparatus, as aforesaid, which can by simple adjustments be rendered capable of handling effectively any desired number of such punches up to the capacity of the machine.
Other objects and purposes of the invention will be apparent to persons acquainted with methods and apparatuses of this general type upon reading the following specification and insepection of the accompanying drawings.